    ; 检测点4-2的正确汇编代码
    mov ax,0xb800                 
    mov ds,ax
    
    mov byte [0x00],'a'
    mov byte [0x02],'s'
    mov byte [0x04],'m'     

    jmp $
    times 510-($-$$) db 0
    db 0x55,0xaa

